Production of metal films



June 24, v1930. w. E. wATKlNs 1,766,417

PRODUCTION OF METAL FILMS Filed Jan. 6, 1927 INVENTOR William E'. Wa t/f/'ns ATTORNEYS the metal to Patented June 24, 1930 i- UNITED STATES WILLIAM E. WATXINS, OF NEW TUBE COMPANY, 0l',v NEW PATENT OFFICE- YORK, N. Y., ASSIGNORfTO COPPER PLATE SHEET AND YORK, N. Y., A. CORPORATION OF NEW JERSEY PRODUCTION OF METAL FILMS Application tiled January 6, 1927. Serial No. 159,337.

of the plating metal on the metal to be plated.

Iplating suspension,

In a prior Patent,4 No. 1,197,693, granted Sept. 12th, 1916, I have described and claimed a process of plating metal in which a metal such as a mixture of an oxide of the plating metal and an oil, is applied to the metal to be plated and the metal heated to reduce the oxide and form a continuous film of the plating metal on the metal to be plated. To insure the reduction of the oxide to metallic form, finely divided carbon, or other reducing agent, may be added to the metal plating suspension as disclosed and claimed in my prior Patent N o. l1,197 ,694, granted Sept. 12th, 1916. The plating metal 1n finel divided form maybe substituted for the re ucible compound and mixed with a suitable vehicle such as a semi-liquid or viscous hydrocarbon and applied to the metal to be plated by coating the base with the plating suspension and heating as described in my prior patent, No. 1,197,695, granted Sept 12th, 1916.

In lating metals according to the processes isclosed in my prior patents, the metal to be coated and the suspension thereon is heated to a temperature above the melting point of the plating metal. Thus, when ferrous metals are coated with copper, the metal is heated to a temperature approximating the melting temperature of copper, or tt a temperature of substantially 2000 F.

VI have found that a superior plated product may be obtained if the metal is heated merely to the sintering tempera-ture of the plating metal. Within their sintering temperature range, metals possess suflcient freedom of movement to enable them to coalesce. I have discovered that by heating the metal to be plated with the metal plating suspension thereon to the sintering temperature of the plating metal, it is possible to produce films of uni ormly beautiful appearance and possessing a degree of continuity not possible when the film has been allowed to reach its melting temperature. Thus, in catin ferrous metals, I propose to heat the meta with the coating applied thereto to a temperature ofY about 1800 F.. which is sufiicient'to permit the copper to coalesce and form a continuous coating. I have further found that the best results are obtained if the film of plating metal is kept below its sintering tem erature until the metal base has reache the proper temperature. I accordingly preheat the base on which the coating film has been applied to a temperature just below the sintering temperature of the plating metal and then raise the temperature to the sintering temperature of the plating metal to form the adherent film or layer on the base.

A further object of the invention is to provide a furnace having a preheating zone in which the metal base may be properly preheated before the plating filmV reaches its sintering temperature. I accordingly provide a furnace having a preheating zone, a heat treating zone, a cooling chamber and a combustion chamber and regulate the passage of the products of combustion through the furnace in such manner that the metal on which the coating has been ilplied is first preheated, then raised to" the sintering` temefore reaching the airto such a temperature that it will not readily oxidize when exposed to air.

In the followin tion I have descri ed Ytheapplication of copper plating to ferrous strips. The invention may be applied to the coating or plating of other metals and other plating-metals may also be' employed. It will be apparent that the process is equally applicable to the coating of plates or sheets as well as strips. a

In the accompanying draw-ings I have diagrammatically illustrated a type of furnace particularly useful in practicing the process and forming a part of the mventlon. In

illustration of the invenprojects through an this showing, Fi 1 is a vertical,-longitudinal, sectional view o the furnace;

Fig. 2 is a vertical, transverse, sectional viev, substantially on line 2-2 of Fig. 1; an

Fig. 3 is a similar view on line 3-3 of Fig. 1.

The furnace is preferabl rectangular and consists of outer Walls, 1, a oor, 2, and a roof, 3, preferably lined with silocel or similar material. Within the furnace I provide side walls, 4` a floor, 5, and an inner roof, 6, o fire brick. The interior of the furnace is in the form of a large rect-angular chamber which is divided at the front by a separating wall, 7, of fire brick forming a preheating chamber, 8, at the top and a combustion chamber, 9, at the bottom. A burner block, 10, is arranged intermediate the ends of the combustion chamber and an oil burner,

opening in this block. The oil burner may be supplied with the proper mixture of air and fuel in any suitable manner. The portion of the furnace in the rear of the preheating zone and combustion chamber forms a heat treating zone, 12. Afoot arch, 13, is arranged at the back of the partition, 7, and curves downwardly to the floor of the furnace so that the products of combustion from the combustion chamber, 9, are forced to travel around this arch in entering the heat treating zone. The hot gases issuing from the combustion chamber are thus divided equally by the foot arch. At the rear of the furnace,'1 provide an opening, and a i cooling chamber, 14, is connected to the furthe various portions of the furnace.

nace at this opening. The cooling chamber is of such length that the strips in passing throu h it will be cooled to such temperature that t ey may then be passed into the open air without danger of oxidation. Suitable rollers, 15, may be arranged at the end of the cooling chamber. A ramp, 16, may be built in the ack of the furnace to prevent the gases from ocketing therein. Suitable means are provi ed for controlling the temperature in A stack, 17, is arranged adjacent the rear of the furnace and communica with the' interior through an opening, 18. The size of this opening may be adjusted by means of slidable dampers, 19. A similar stack, 20, is arran ed at the rear of the cooling chamber and the ow of gases throu h this stack is controlled by a damper, 21. stack, 22, is arranged a 'afront of the furnace and provi ed with a damper, 23. A baie, 2.4, may be arranged depending from the roof of the furnace and. separating the preheating zone from the heat treating zone. The strip of metal to be treated is passed throu h the furnace in catena form as indicated at A and as described an claimed in my copending application, Serial No. 144,685, filed October 28th, 1926.l The strip is supported by the nace.

rollers, 15, in the cooling'chamber and by a suitable guide, 25, arranged at the front of the furnace.

In practicing the process the strip is rst coated on one or both sides with a suspension of a reducible compound of the plating metal or the metal in finely divided uid spreading medium of a reducing character which serves to protect both the plating metal and the metal to be lated during the plating operation. An asp altic base hydrocarbon oil havin@` a viscosity of 116 has been found satisfactory as possessing the proper spreading and binding qualities while its base contains sufficient carbon to reduce any oxides that ma be present. When 5 grammes or less of tile plating metal is to be applied to each square foot of surface, the finely divided metal and oil are mixed in the proportion of 40 per cent finely divided metal and 60 per cent oil. For films of greater thickness a mixture richer in finely divided metal has been found satisfactory. The metal strip is passed through the furnace and the products of combustion from the burner, 11, pass from the combustion chamber around the foot arch, 13, into the heat treating chamber, 12. The temperature to be maintained in the heat treating chamber will depend upon the speed of travel of the metal being treated. In a furnace of this type, approximately .25 feet long, the heat treating zone may be maintained at a temperature of.2250 F. to treat a strip 12 x .05 when the strip is traveling at a speed of 80 feet per minute. Under these conditions the strip will be heated to altemperature of substantially 1800 F., in passing through the heat treating zone. A pyrometer, 26, may be placed zone by passing it through the wall or roof of the furnace. The preheating zone may alsobe provided with a pyrometer, 27, and the temperature in the preheating zone should be maintained under that of the heat treating zone to prevent the plating metal from reaching its sintering temperature before the metal base is at the right temperature to receive 1t. The furnace gases should be slightly reducing and maintained at a pressure suflicient to prevent leakage of atmospheric air in the fur- The pressure ,within the furnace causes the gases to travel in both directions when they enter the heat treating zone thereby causing a portion of the gases to pass through the preheating zone to the stack. 22. The baille, 24, retards the flow of gases into the preheating zone and thus assists in maintaining a lower temperature in this zone than in the heat treating zone. The temperature of the preheating zone may also be re ulated bythe damper, 23. The main contro of the flow of gases toward the preheating zone and the coolin chamber,l14, is accomplished by means of hesliding blocks or dampers, 19, over the opening, 1,8,and by ,properly reguform and a liqlating the size of the opening, 18, the temperature in the various zones may be positively controlled. The furnace may be operated at constant temperatures in the several zones and the speed'of travel of the metal through the furnace may be regulated to suit the gauge of the metal vbeing treated. The process can, of

course, be modified to treat different metals and in each instance, the temperature of the heat treating zone and the speed oftravel of the strip is regulated to heat the metal to the sintering temperature of the plating metal. To produce a bronze plating, the plating suspension is formed of a mixture ofcupric oxide and tin oxide (or, preferably, finely divided copper, and tin oxide) in definite proportions to produce the desired bronze, to which the proper quantity of the spreading vehicle or oil isadded.

The furnace construction disclosed herein forms the subject matter of a divisional ap plication filed June 25, 1927, Serial Number 201,317. y

- I claim;

1. The herein described essentially of coating the metal to be plated with a plating suspension of the plating metal, and then heating it to the sintering temperature of the plating metal for suiicient time to form an adherent film of the'vplating metal on the plated metal. i

2. The herein described process consisting essentially of coating ferrous metal with a plating suspension of copper, and then heating it to the sintering temperature of copper for sufficient time to form'anadherent Afilm of copper on the ferrous metal.

3. The herein described process consisting Aessentially of coating ferrous metal with a mixture of finely divided copper and an oil, and then heating it to approximately the sintering temperature of copper for a sufiil essentially of coating the cient length of time to form an adherent film of copper on the ferrous metal.

. 4. The herein described process consisting metal to be plated -with a plating suspension of the plating metal, preheating it to a temperature below the sintering temperature of the plating metal, and then heating it substantially to the sintering temperature of the plating metal for suflicient time to form an adherent film of the plating metal on the plated metal.

5. The herein described process consisting essentially of coating the metal to be plated with a plating suspension of the plating metal in finely divided form and an oil, preheating it to atemperature below the slntering, temperature of the plating metal, and then heating it to substantially the sintering temperature of the plating metal to form an adherelt film of the plating metal on the plated meta 6. The herein described process consisting process consisting suspension to a degree just under its melting temperature for a suflicient time to form a'n adherent film ofthe metal to be plated.

plating metal' on the l In testimony whereof I aliix my si nature. i

WILLIAM E. WAT INS. 

